Molding-core



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Specificiition of Letters Patent. Fgygggmgdl gewinn leggi `Molding-Core,of which the following isa specification.

This invention relates to the art of molding or vulcanizing an articleof manufacture formed in `Whole or in part of rubber wher in it isdesired to provide Within said article a void which is rigidi supportedagainst internal collapse throng out the vulcanizing process.l Theinvention,"by Way of illustra* tion only, is shown and described asparticularly applied to the formation of semi-solid tires, such, forinstance, as those designed for use on heavy duty motor trucks.

ln the manufacture of semi-solid tires the prevailing practice resortedto in the formation of internal voids for increasingtlieir resiliency,as well also as for econoinizing the stock used in their manufacture,implies the-employment of rigid internal supports to maintain the voidsduring vulcanization; the internal support heingthereaiter with drawn inan appropriate-manner to leave the void freeto function as a resilientchainw ber. ln the choice of suitable internal supports the followingtypes are most common:

drels which are destructihle Within the voids.

rigid non-destructible mandrels which must he lahoriously extracted;initially rigid inenhut must he extracted, for instance, those made ofmaterial such as bismuth, lead and tin, so'coinpounded that they meltunder the heat of vulcanization after the body oni the structure hasbecomesetg"and lastly, supports comprising inflatable means whereby afluid pressure may loe maintained during1 vulcanization, these lastnamed means usually remaining Within the structure in del'latedconditionu `Being cognizant of the shove and inrecognition of theinherent detects ci such expedients from the viewpoint off mamita@ astrata of hard rubber 'if' t formed direct upon the unitari f heat andpressure of vulcanieation, yet have its properties suliseiuently semodified hv the heat treatmentas to be readily pulifeiizeli intoharmless particles Within the void it creates, The destruction beingaccomplished 60 hy iinpact, fishy the use of the tire in actul service,whereby the resiliency of the ine-ss will he restored without thenecessitiT ot re+ movingr the torni heitere the tire is put intoservice.

An additional oliject is to forni the slielllike support o' materialthat will hev so completely disintegrated hy the incidental shocksof'service as to ohviate all possibility of internal/injury by cutting'er ahradi g, 70 and at the saine time to set up ne chemicallydeleterious reaction Within the niassn With these and additional objectsin view, as more fully herein set forth, the invention consists et thenevel'ineans provided 75 and the associated use thereof in. combinationwith its particular environment.

Referring to the drawings;

Figure l illustrates a preferred torni and placement of a shell coreWithin a laminated 80 tire structure. The View being perspective of efragment of e tire.,

Fig. i2 is similar to except the tirev structure illustrated :is o theusual eX- triidecl type 'with the veld farther troie the Se rim.

ln Fig. l the treiis terrified ci? tliin strips of uiivulcenized ruhlaers e metallic heee ring 6, and neu must he created concurrent with tionci the structure, hy oinittiii, e the winding aclaceiit the shell core8, which, of course, is placedupon the riin prior te t5 the Windingoperation. 'lllio cere 8 is illusn trated asseini-circuler in cross.section and formed as an annulus laid snugly 'against the hase coat` 7.ln Fig. il the tire ti is extruded type wherein the s. i in indeinitestrai lengths tlirougli which is fashion' to iinpert the void.. 'llextruded is afterward formed as an eiiiiulus aliena,

out te end i' the customery ice riin 6 and seated in the n d hase l'.The core 10 tor this 'type is ill rated es an. iiiclosed sectional Ecrinend is :cduced in an appropriate manner within? the void rior to bendingthe tire around the .tery the '110 purpose of introducing the corewithin the void it may bffconstructed in straight lengths .of materialsuliiciently flexible to be bent to the required curvature. The wore, itin straight lengths may be incloscd within a sleeve running lengthwiseofthe bore ol: the extruding machine 'and fed through the kporltion ofthe die that creates the void in the .whereby it may be readilydisintegrated in Service. lThe chemical proportion of the core are notan element of this invention and may be xed at will to impart thephysical properties desired for any given manufacturing condition andwill depend upon the particular proportions of the void to be supportedand upon the duration and intensity of the curing heat and bear adefinite relation to the molding pressure; all of which is a matter ofdetail readily ascertained by those well skilled inthe art.

v Although theillustrative embodiment of this invention has taken aparticular form it will be understood that it may be practised through awide range l,Without departing from the scopeand spirit of the appendedclaims.

1. A molding support for preserving a void in the interior of an articleof manufacture consisting of vulcanizable material, comprising a formedshell-like hollow structure composed of partially vulcaniaed materialand adapted to become brittle` and readily destroyed after the articlesupported is vulcanized.

2. A molding support of the character described, comprising a formedshell-like structure of partially vulcanized material-adapted topreserve a void interior-ly of an annulus of rubber duringvulcanization` under heat and pressure, said support being adapted tobecome hard and brittle under the heat of vulcanization while serving asa support whereby its destruction by impact is facilitated.

3. A molding support of the character described, comprising a shell-likehollow annulus composed of a formed substance having resilientproperties, said support being adapted to become less resilient undersubsequent-heat whereby its destruction by impact is facilitated.

4. A molding support of the character described comprising a brittleshell-like hollow annulus adapted to lill and support an internal voidin a tire structure during vulcanization whereby the void isfpreserved,said support being readily destructible under impact whereby theresiliency of the tire is increased. .I

5. rl`he combination with an annular steel rim having a vulcanizablestructure thereon,

oi' a hard shell-like annular support within said structure forming avoid therein and adapted to be readily destroyed by impact aftervulcanization whereby the`resiliency of the structure is increased.

6. The process of forming an` article of manufacture composed ofvulcanizablemateria-l comprising the following steps: (a) providing saidarticle with an internal void Y(b) filling said void with a hollowshell-like support adapted to preserve its integrity duringvulcanization (c) vulcanizing the article interiorly supported wherebythe sup port becomes brittle (d) breaking the brittle supportai'tervulcanization whereby the void contributes to the resiliency of thearticle.

ln testimony whereof I allix my signature.

THOMAS C. MARSHALL.

